In creating a machining program to cause a machine tool to operate, CAM (Computer Aided Manufacturing) is often used, but specified positions and attitudes created with the CAM may include a truncation error in convergence calculation or a rounding error due to the limit of the number of output digits. Although the trajectory originally desired to be represented is smooth, because of these errors, the smoothness of the trajectory may be lost when drawn by outputted instructions, or minute back-and-forth movement along a specific axis may occur.
Instructions to produce an unsmooth trajectory as above may cause vibration when the machine operates or scratches in a worked surface. Accordingly, in order to avoid these, functions to smooth instructions in a machining program have conventionally been used. As such a technique, there is a technique described in, e.g., Patent Literature 1.
Patent Literature 1 discloses a technique where instruction data of specified points obtained by approximating a curved line by line segments is smoothed to obtain a curved line, where the specified points are corrected in units smaller than the minimum unit of the instruction data with use of the smoothed curved line and a tolerance amount indicating a set allowable correction amount, where thus the acceleration of a machine tool when driven is made smaller, and where speed is computed using the corrected specified points such that the acceleration of each movement component falls within a prescribed value so as to perform speed control.